• Biomolecules & Therapeutics
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• v.18 no.4
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• pp.375-385
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• 2010

Conventional cancer chemotherapy is seriously limited by tumor cells exhibiting multidrug resistance (MDR), which is caused by changes in the levels or activity of membrane transporters that mediate energy-dependent drug efflux and of proteins that affect drug metabolism and/or drug action. Cancer scientists and oncologists have worked together for some time to understand anticancer drug resistance and develop pharmacological strategies to overcome such resistance. Much focus has been on the reversal of the MDR phenotype by inhibition of ATP-binding cassette (ABC) drug transporters. ABC transporters are a family of transporter proteins that mediate drug resistance and low drug bioavailability by pumping various drugs out of cells at the expense of ATP hydrolysis. Many inhibitors of MDR transporters have been identified, and though some are currently undergoing clinical trials, none are in clinical use. Herein, we briefly review the status of MDR in human cancer, explore the pathways of MDR in chemotherapy, and outline recent advances in the design and development of MDR modulators.

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.539-547
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• 1990

Molecular Orbital calculations using the SC-MEH method have been carried out for the interaction of Adenine, Guanine and Cytosine as DNA base and diaminecytosineplatinum(DCP) in various conformations. The results showed that the order of DCP binding to the DNA bases was guanine > adenine > cytosine and the stabilization energy of cis-isomer was larger than that of trans-isomer in the adenine-DCP complexes system. Furthermore, platinum(II) binding to DNA bases markedly gives rise to change of atomic charge in DNA bases ring, which can explain anti-tumor activity of platinum complex.

• The Korean Journal of Ceramics
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• v.1 no.4
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• pp.209-213
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• 1995

The electrical conductivity was investigated in two series of alkali aluminosilicate glass melts, $25R_2O(R: Na and K)-xAl2O3-(75-x)SiO_2$ at temperatures ranging from 1000 to 140$0^{\circ}C$. The dependences of conductivity or activation energy on $Al_2O_3/R_2O$ of both series in the molten state showed a same behavior. These results in the molten state were compared with previous studies for sodium alkali aluminosilicate glasses in the molten and solid state, and explained in terms of the binding state: $[-O]-R^+\; and\; [AlO_4]-R^+$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.3
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• pp.146-150
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• 2014

As a method of simple patterning of transparent conductive oxide (TCO) films deposited on flexible substrates, laser direct etching was carried out on TCO films sputtered on polycarbonate (PC) substrates. As a result of different binding energies in TCO films, indium tin oxide (ITO) and indium gallium zinc oxide (IGZO) were more easily etched than zinc oxide with different $Nd:YVO_4$ laser beam conditions.

• Bulletin of the Korean Chemical Society
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• v.28 no.2
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• pp.241-245
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• 2007

The electronic structures of the new organic conducting salts, the β'- and β''-phases of (BEDT-TTF)2[(IBr2)0.2(BrICl)0.1(ICl2)0.7], were examined by calculating their electronic band structures, Fermi surfaces and HOMO-HOMO interaction energies using the extended Huckel tight binding method. On the basis of these calculations, we probed why the β'-phase is semiconducting while the β ''-phase is metallic.

• Textile Coloration and Finishing
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• v.25 no.3
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• pp.153-158
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• 2013

In this study, pyrene based chemosensor was synthesized by two step reaction. The chemosensor showed that high selectivity toward fluoride in DMSO. The fluorescence intensity was drastically increased by binding between chemosensor and fluoride ion. Absorption and fluorescence spectra were obtained by UV-Vis spectrometer and fluorescence spectrophotometer. The binding ratio between chemosensor and fluoride ion was also investigated by job's plot method and Benesi-Hildebrand plot. The HOMO/LUMO energy levels and electron distribution were calculated and simulated by Material studio 6.0 Package.

• Bulletin of the Korean Chemical Society
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• v.22 no.11
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• pp.1248-1254
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• 2001

The conformations and energies of p-tert-butylcalix[4]crown-6-ether (1) and its alkyl ammonium complexes have been calculated by ab initio HF/6-31G quantum mechanics method. The cone conformation was found to be most stable for free host 1. We hav e determined the binding site of these host-guest complexes focusing on the crown-6-ether or p-tert-butylcalix[4]arene pocket of the cone conformation of host molecule 1. The primary binding site of host 1 for the recognition of alkyl ammonium guests was confirmed to be the central part of the crown moiety of cone conformation. The complexation energy calculations revealed that the ammonium cation without alkyl group showed the highest complexation efficiency when combined with host 1, that is in satisfactory agreement with the experimental results.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.293-300
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• 2018

Lipocalins are diverse group of small extracellular proteins found in various organisms. In this study, members of 10 non-homologous lipocalin-ligand crystal complex structures were remodeled using rigid and flexible ligand modes to validate the prediction efficiency of molecular docking simulation. The modeled ligand conformations indicated a high prediction accuracy in rigid ligand mode using cluster based analysis for most cases whereas the flexible ligand mode required further considerations such as ligand binding energy and RMSD for some cases. This in silico study is expected to serve as a platform in the screening of novel ligands against lipocalin family of proteins.

• Progress in Superconductivity
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• v.10 no.2
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• pp.69-73
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• 2009

For extraction of the self-energy from the angle resolved photoemission spectroscopy(ARPES) experiments for the cuprate superconductors, the momentum distribution curve(MDC) analysis is commonly used. There are two requirements for this method to work: the self-energy is momentum independent and the bare electron dispersion is known. Assuming that the first condition is satisfied in the cuprates, we checked the effects of the bare dispersion on the extracted self-energy. For this, we first generated the ARPES intensity using the tight-binding band of the B2212 by solving the Eliashberg equation. We then extracted the self-energy from the theoretically generated ARPES intensity using the linear and quadratic dispersions. By choosing the bare dispersion such that the Kramer-Kronig relation is best satisfied between the real and imaginary parts of the extracted self-energy, we confirmed that the quadratic dispersion is better for the bare electron band for Bi2212. The self-energy can be reasonably extracted from the ARPES experiments using the MDC analysis.

• Clean Technology
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• v.21 no.3
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• pp.200-206
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• 2015

In order to investigate the effect of cerium oxide addition, Cu-ZnO-CeO₂ catalysts were prepared using co-precipitation method for water gas shift (WGS) reaction. A series of Cu-ZnO-CeO₂ catalyst with fixed Cu Content (50 wt%, calculated as CuO) and a given ceria content (e.g., 0, 5, 10, 20, 30, 40 wt%, calculated as CeO₂) were tested for catalytic activity at a GHSV of 95,541 h^-1, and a temperature range of 200 to 400 ℃. Cu-ZnO-CeO₂ catalysts were characterized by using BET, SEM, XRD, H₂-TPR, and XPS analysis. Varying composition of Cu-ZnO-CeO₂ catlysts led the difference characteristics such as Cu dispersion, and binding energy. The optimum 10 wt% doping of cerium facilitated catalyst reduction at lower temperature and improved the catalyst performance greatly in terms of CO conversion. Cerium oxide added catalyst showed enhanced activities at higher temperature when it compared with the catalyst without cerium oxide. Consequently, ceria addition of optimal composition leads to enhanced catalytic activity which is attributed to enhanced Cu dispersion, lower binding energy, and hindered Cu metal agglomeration.